When a thrombosis occurs in the left calf, it is important to distinguish whether the thrombosis is superficial or deep vein thrombosis. If it is a superficial vein thrombosis, the patient’s symptoms are more limited and may include thromboangiitis at the site of thrombosis, such as redness and swelling of the skin, increased skin temperature, tenderness, and the ability to palpate hard streaks. In this case, the patient feels very painful and comes to the hospital for treatment. In the case of deep vein thrombosis in the lower extremities, such as thrombosis of the intermuscular veins, or thrombosis of the peroneal, anterior tibial, or posterior tibial veins, the patient presents with swelling of the legs, increased skin tension, increased temperature, and reddening of the skin. If the patient’s condition is prolonged, it can cause finger sunken edema of the skin, which can be aggravated during activity.